After digital sculpting is complete, the model is passed to Technical Directors who apply bones/muscles and controls. Also layers of visual effects can be added (smoke, fire, sparks, glowing things). This process is actually very complex and time consuming.

At this point the character has become what is called a "digital asset". It can move through the production pipeline to different departments. It might go back for more sculpting, go to the rendering departing for lighting, go to texture artists for painting, etc.. etc..

The animators will bring the character to life by key framing the motion. They work on shots and sequences assigned to them by a producer. They can acquire data from another department in the form of data files captured during motion capture sessions with an actor. While an actor might have performed motion capture sessions, an animator is still required to clean and apply the sequence to the character. A lot of people think motion capture makes things easier, but it doesn't. It's a challenge to work with.

You can read more about VFX processes at CGSociety. The Wrath of The Titans is a recent example.

This question actually dates back to some of the debates in animation. How much of a character is the director, writers, and artists and how much is a part of the voice artists providing the character.

This debate is what has often fueled the salary battles of actors from "The Simpsons" as well as an endless history of industry strikes.

"The Avengers" opted to use motion capture on Mark Ruffalo so that the Hulk would actually resemble Banner not merely in features but in expression. So as the effects and CGI improve, there seems to still be a desire to have a human being actually perform (Lord of the Rings, Avatar, Rise of the Planet of the Apes, etc) Back on the topic of voice, Lou Ferrigno returned as the voice.

So the question of "Real Entity" vs. "Pure CGI" is left as a constant debate in the industry. even fully CG characters such as "Otto" the auto-pilot in "WALL-E" still have their grounding in an artist and director. Though, I believe this may be the closest to date as a Pure-CG character since the voice was fully CG Generated as well.

It should be noted that, in the case of Wall-e, both Wall-e and EVE used (post-processed) phlanged voices from real people. Otto (the auto-pilot), however, was 'voiced' by the standard Mac text-to-speech synthesizer. All Pixar animation has been done by hand, meaning no motion capture.
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Clockwork-MuseMay 4 '12 at 20:13